# How to calculate transformer winding losses

1. ## How to calculate transformer winding losses

Hi,

We used a transformer from payton for +330V to 50V Half bridge LLC converter.Refer the datasheet attached,
In that transformer losses is given as 26W.
Also practically we observed the same losses in transformer.
Payton provide the loss details as below based on our request.
They told that additional loss is due to parasitic leakage inductanceAttachment 156028.
How to calculate these additional losses?  Reply With Quote

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2. ## Re: How to calculate transformer winding losses

You attachment 156028 returns an "invalid attachment" error.

I am also curious what they mean parasitic leakage inductance losses.

What I can recall from leakage inductance; that it is uncoupled inductance that will ring with parasitic capacitances which will produce severe ringing. That ringing can generate a voltage breakdown in switching semiconductors, and must be snubbed. The snubbers, at least the simple ones, will dissipate that energy as heat in a resistor. Which of course is a power loss which reduces the efficiency.

But those are snubber losses. Transformers and inductor losses consist only of core or copper losses. And each has its own sub-losses: i.e. copper may divided into RDC, skin effect, fringing, etc.  Reply With Quote

3. ## Re: How to calculate transformer winding losses

Hi,

To be honest: I don´t know the answer.

* maybe the copper loss is tested with DC. Then there are additional losses caused by AC: Proximity effect and skin effect.

***
It causes the output voltage to be less than ideal... but the current is almost ideal: U_in x I_in is higher than U_out x I_out ... but I expect it to cause phase shift rather than heat.

Klaus  Reply With Quote

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4. ## Re: How to calculate transformer winding losses

Did you try to detetmine the loss components yourself? The quoted statement can't be found in the datasheet. "Loss due to parasitic leakage inductance" doesn't sound like a serious substantiation. A possible explanation might be the difference between theoretical core losses of the basic transformer and real core losses according to fringing fields, flux perpendicular to main magnetic path etc.  Reply With Quote

5. ## Re: How to calculate transformer winding losses

They told that additional loss is due to parasitic leakage inductance
Is a round-a-bout way of saying there are proximity losses in the copper wdgs associated with the windings - these losses are lower for higher coupling factor ( lower leakage )

and are proportional to load current - so 15W of extra Cu heating and full power, 7.5W at half power etc ...

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6. ## Re: How to calculate transformer winding losses

From the measured leakage inductance in the realized transformer,Is it possible to calculate the losses due to leakage inductance?
So that we can plan thermal constraints of transformer.  Reply With Quote

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7. ## Re: How to calculate transformer winding losses

it is part of the overall losses and does not lend itself to exact calculation - frequency makes a difference as does the shape of the currents flowing - no doubt the data sheet figures are derived from sine wave currents which give the lowest loss figures - heatsinking and max hot spot temp also affect losses ...  Reply With Quote

8. ## Re: How to calculate transformer winding losses

Yes, your transformer appears to be an planar transformer, and appears to have leakage inductance designed into it deliberately so its an Integrated transformer .
Deliberate design-in of leakage inductance is common in LLC transformers, so there are not really losses associated with it (at least not directly). But I think you probably know this.
Though of course, if there is increased circulating current due to resonant component choices, than that will be like a conduction loss  Reply With Quote

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